| 1. |
- Aase-Remedios, Madeleine E., et al.
(författare)
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Evolution of the Spider Homeobox Gene Repertoire by Tandem and Whole Genome Duplication
- 2023
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Ingår i: Molecular biology and evolution. - : Oxford University Press. - 0737-4038 .- 1537-1719. ; 40:12
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Tidskriftsartikel (refereegranskat)abstract
- Gene duplication generates new genetic material that can contribute to the evolution of gene regulatory networks and phenotypes. Duplicated genes can undergo subfunctionalization to partition ancestral functions and/or neofunctionalization to assume a new function. We previously found there had been a whole genome duplication (WGD) in an ancestor of arachnopulmonates, the lineage including spiders and scorpions but excluding other arachnids like mites, ticks, and harvestmen. This WGD was evidenced by many duplicated homeobox genes, including two Hox clusters, in spiders. However, it was unclear which homeobox paralogues originated by WGD versus smaller-scale events such as tandem duplications. Understanding this is a key to determining the contribution of the WGD to arachnopulmonate genome evolution. Here we characterized the distribution of duplicated homeobox genes across eight chromosome-level spider genomes. We found that most duplicated homeobox genes in spiders are consistent with an origin by WGD. We also found two copies of conserved homeobox gene clusters, including the Hox, NK, HRO, Irx, and SINE clusters, in all eight species. Consistently, we observed one copy of each cluster was degenerated in terms of gene content and organization while the other remained more intact. Focussing on the NK cluster, we found evidence for regulatory subfunctionalization between the duplicated NK genes in the spider Parasteatoda tepidariorum compared to their single-copy orthologues in the harvestman Phalangium opilio. Our study provides new insights into the relative contributions of multiple modes of duplication to the homeobox gene repertoire during the evolution of spiders and the function of NK genes.
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| 2. |
- Budd, Graham, et al.
(författare)
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Comment on "The lower Cambrian lobopodian Cardiodictyon resolves the origin of euarthropod brains"
- 2023
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 380:6652
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Tidskriftsartikel (refereegranskat)abstract
- Strausfeld et al. (Report, 24 Nov 2022, p. 905) claim that Cambrian fossilized nervous tissue supports the interpretation that the ancestral panarthropod brain was tripartite and unsegmented. We argue that this conclusion is unsupported, and developmental data from living onychophorans contradict it.
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| 3. |
- Damen, Wim, et al.
(författare)
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Embryonic development and the understanding of the adult body plan in myriapods
- 2009
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Ingår i: Soil Organisms. - 1864-6417. ; 81:3, s. 337-346
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Tidskriftsartikel (refereegranskat)abstract
- The adult body plan is laid down during embryonic and post-embryonic development of an organism. Here we review two examples for how data on gene expression during embryonic development have changed our understanding of the adult body plan of myriapods. Gene expression studies in the geophilomorph centipede Strigamia maritima (Leach, 1817) have demonstrated that a developmental constraint underlies the always-odd number of leg bearing segments in geophilomorph centipedes. Similarly, data on gene expression in the millipede Glomeris marginata (Villers, 1789) have demonstrated a decoupling of dorsal and ventral segmentation, which provided an explanation for the discrepancy in dorsal and ventral structures in the body of millipedes. Knowledge on the molecular mechanisms underlying embryonic development therefore significantly contributes to understanding morphological features of the adult myriapod body.
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| 4. |
- Damen, Wim, et al.
(författare)
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Pair rule gene orthologs in spider segmentation
- 2005
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Ingår i: Evolution & Development. - 1520-541X .- 1525-142X. ; 7:6, s. 618-628
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Tidskriftsartikel (refereegranskat)abstract
- The activation of pair rule genes is the first indication of the metameric organization of the Drosophila embryo and thus forms a key step in the segmentation process. There are two classes of pair rule genes in Drosophila: the primary pair rule genes that are directly activated by the maternal and gap genes and the secondary pair rule genes that rely on input from the primary pair rule genes. Here we analyze orthologs of Drosophila primary and secondary pair rule orthologs in the spider Cupiennius salei. The expression patterns of the spider pair rule gene orthologs can be subdivided in three groups: even-skipped and runt-1 expression is in stripes that start at the posterior end of the growth zone and their expression ends before the stripes reach the anterior end of the growth zone, while hairy and pairberry-3 stripes also start at the posterior end, but do not cease in the anterior growth zone. Stripes of odd-paired, odd-skipped-related-1, and sloppy paired are only found in the anterior portion of the growth zone. The various genes thus seem to be active during different phases of segment specification. It is notable that the spider orthologs of the Drosophila primary pair rule genes are active more posterior in the growth zone and thus during earlier phases of segment specification than most orthologs of Drosophila secondary pair rule genes, indicating that parts of the hierarchy might be conserved between flies and spiders. The spider ortholog of the Drosophila pair rule gene fushi tarazu is not expressed in the growth zone, but is expressed in a Hox-like fashion. The segmentation function of fushi tarazu thus appears to be a newly acquired role of the gene in the lineage of the mandibulate arthropods.PMID:16336415
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| 5. |
- Eriksson, Bo Joakim, et al.
(författare)
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Head patterning and Hox gene expression in an onychophoran and its implications for the arthropod head problem
- 2010
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Ingår i: Development, Genes and Evolution. - : Springer Science and Business Media LLC. - 0949-944X .- 1432-041X. ; 220:3-4, s. 117-122
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Tidskriftsartikel (refereegranskat)abstract
- The arthropod head problem has puzzled zoologists for more than a century. The head of adult arthropods is a complex structure resulting from the modification, fusion and migration of an uncertain number of segments. In contrast, onychophorans, which are the probable sister group to the arthropods, have a rather simple head comprising three segments that are well defined during development, and give rise to the adult head with three pairs of appendages specialised for sensory and food capture/manipulative purposes. Based on the expression pattern of the anterior Hox genes labial, proboscipedia, Hox3 and Deformed, we show that the third of these onychophoran segments, bearing the slime papillae, can be correlated to the tritocerebrum, the most anterior Hox-expressing arthropod segment. This implies that both the onychophoran antennae and jaws are derived from a more anterior, Hox-free region corresponding to the proto and deutocerebrum of arthropods. Our data provide molecular support for the proposal that the onychophoran head possesses a well-developed appendage that corresponds to the anterior, apparently appendage-less region of the arthropod head.
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| 6. |
- Gasiorowski, Ludwik, et al.
(författare)
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Molecular evidence for a single origin of ultrafiltration-based excretory organs
- 2021
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Ingår i: Current Biology. - : Elsevier. - 0960-9822 .- 1879-0445. ; 31:16, s. 3629-
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Tidskriftsartikel (refereegranskat)abstract
- Excretion is an essential physiological process, carried out by all living organisms, regardless of their size or complexity.(1-3) Both protostomes (e.g., flies and flatworms) and deuterostomes (e.g., humans and sea urchins) possess specialized excretory organs serving that purpose, Those organs exhibit an astonishing diversity, ranging from units composed of just few distinct cells (e.g., protonephridia) to complex structures, built by millions of cells of multiple types with divergent morphology and function (e.g., vertebrate kidneys).(4,5) Although some molecular similarities between the development of kidneys of vertebrates and the regeneration of the protonephridia of flatworms have been reported, (6,7) the molecular underpinnings of the development of excretory organs have never been systematically studied in a comparative context. (4) Here, we show that a set of transcription factors (eya, six1/2, pou3, sail, Ihx1/5, and osr) and structural proteins (nephrin, kirre, and zo1) is expressed in the excretory organs of a phoronid, brachiopod, annelid, onychophoran, priapulid, and hemichordate that represent major protostome lineages and non-vertebrate deuterostomes. We demonstrate that the molecular similarity observed in the vertebrate kidney and flatworm protonephridia(6,7) is also seen in the developing excretory organs of those animals. Our results show that all types of ultrafiltration-based excretory organs are patterned by a conserved set of developmental genes, an observation that supports their homology. We propose that the last common ancestor of protostomes and deuterostomes already possessed an ultrafiltration-based organ that later gave rise to the vast diversity of extant excretory organs, including both proto- and metanephridia.
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| 7. |
- Harper, Amber, et al.
(författare)
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Widespread retention of ohnologs in key developmental gene families following whole-genome duplication in arachnopulmonates
- 2021
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Ingår i: G3. - : Oxford University Press. - 2160-1836. ; 11:12
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Tidskriftsartikel (refereegranskat)abstract
- Whole-genome duplications (WGDs) have occurred multiple times during animal evolution, including in lineages leading to vertebrates, teleosts, horseshoe crabs, and arachnopulmonates. These dramatic events initially produce a wealth of new genetic material, generally followed by extensive gene loss. It appears, however, that developmental genes such as homeobox genes, signaling pathway components and microRNAs are frequently retained as duplicates (so-called ohnologs) following WGD. These not only provide the best evidence for WGD, but an opportunity to study its evolutionary consequences. Although these genes are well studied in the context of vertebrate WGD, similar comparisons across the extant arachnopulmonate orders are patchy. We sequenced embryonic transcriptomes from two spider species and two amblypygid species and surveyed three important gene families, Hox, Wnt, and frizzled, across these and 12 existing transcriptomic and genomic resources for chelicerates. We report extensive retention of putative ohnologs, further supporting the ancestral arachnopulmonate WGD. We also found evidence of consistent evolutionary trajectories in Hox and Wnt gene repertoires across three of the six arachnopulmonate orders, with interorder variation in the retention of specific paralogs. We identified variation between major clades in spiders and are better able to reconstruct the chronology of gene duplications and losses in spiders, amblypygids, and scorpions. These insights shed light on the evolution of the developmental toolkit in arachnopulmonates, highlight the importance of the comparative approach within lineages, and provide substantial new transcriptomic data for future study.
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| 8. |
- Heingård, Miriam, et al.
(författare)
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FoxB, a new and highly conserved key factor in arthropod dorsal-ventral (DV) limb patterning
- 2019
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Ingår i: EvoDevo. - : BMC. - 2041-9139. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Forkhead box (Fox) transcription factors evolved early in animal evolution and represent important components of conserved gene regulatory networks (GRNs) during animal development. Most of the researches concerning Fox genes, however, are on vertebrates and only a relatively low number of studies investigate Fox gene function in invertebrates. In addition to this shortcoming, the focus of attention is often restricted to a few well-characterized Fox genes such as FoxA (forkhead), FoxC (crocodile) and FoxQ2. Although arthropods represent the largest and most diverse animal group, most other Fox genes have not been investigated in detail, not even in the arthropod model species Drosophila melanogaster. In a general gene expression pattern screen for panarthropod Fox genes including the red flour beetle Tribolium castaneum, the pill millipede Glomeris marginata, the common house spider Parasteatoda tepidariorum, and the velvet worm Euperipatoides kanangrensis, we identified a Fox gene with a highly conserved expression pattern along the ventral ectoderm of arthropod and onychophoran limbs. Functional investigation of FoxB in Parasteatoda reveals a hitherto unrecognized important function of FoxB upstream of wingless (wg) and decapentaplegic (dpp) in the GRN orchestrating dorsal-ventral limb patterning.
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| 9. |
- Heingård, Miriam, et al.
(författare)
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The forkhead box containing transcription factor FoxB is a potential component of dorsal-ventral body axis formation in the spider Parasteatoda tepidariorum
- 2020
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Ingår i: Development, Genes and Evolution. - : SPRINGER. - 0949-944X .- 1432-041X. ; 230:2, s. 65-73
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Tidskriftsartikel (refereegranskat)abstract
- In the spider, determination of the dorsal-ventral body (DV) axis depends on the interplay of the dorsal morphogen encoding gene decapentaplegic (Dpp) and its antagonist, short gastrulation (sog), a gene that is involved in the correct establishment of ventral tissues. Recent work demonstrated that the forkhead domain encoding gene FoxB is involved in dorsal-ventral axis formation in spider limbs. Here, Dpp likely acts as a dorsal morphogen, and FoxB is likely in control of ventral tissues as RNAi-mediated knockdown of FoxB causes dorsalization of the limbs. In this study, we present phenotypes of FoxB knockdown that demonstrate a function in the establishment of the DV body axis. Knockdown of FoxB function leads to embryos with partially duplicated median germ bands (Duplicitas media) that are possibly the result of ectopic activation of Dpp signalling. Another class of phenotypes is characterized by unnaturally slim (dorsal-ventrally compressed) germ bands in which ventral tissue is either not formed, or is specified incorrectly, likely a result of Dpp over-activity. These results suggest that FoxB functions as an antagonist of Dpp signalling during body axis patterning, similarly as it is the case in limb development. FoxB thus represents a general player in the establishment of dorsal-ventral structures during spider ontogeny.
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| 10. |
- Hogvall, Mattias, et al.
(författare)
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Analysis of the Wnt gene repertoire in an onychophoran provides new insights into the evolution of segmentation
- 2014
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Ingår i: EvoDevo. - : Springer Science and Business Media LLC. - 2041-9139. ; 5, s. 14-
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Tidskriftsartikel (refereegranskat)abstract
- Background: The Onychophora are a probable sister group to Arthropoda, one of the most intensively studied animal phyla from a developmental perspective. Pioneering work on the fruit fly Drosophila melanogaster and subsequent investigation of other arthropods has revealed important roles for Wnt genes during many developmental processes in these animals. Results: We screened the embryonic transcriptome of the onychophoran Euperipatoides kanangrensis and found that at least 11 Wnt genes are expressed during embryogenesis. These genes represent 11 of the 13 known subfamilies of Wnt genes. Conclusions: Many onychophoran Wnt genes are expressed in segment polarity gene-like patterns, suggesting a general role for these ligands during segment regionalization, as has been described in arthropods. During early stages of development, Wnt2, Wnt4, and Wnt5 are expressed in broad multiple segment-wide domains that are reminiscent of arthropod gap and Hox gene expression patterns, which suggests an early instructive role for Wnt genes during E. kanangrensis segmentation.
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